Eligible patients were randomly selected from the total pool of people who applied through the Immune Tolerance Network. Patients will receive at least 10,000 "islet equivalents" per kilogram (2.2 pounds) of body weight. This likely will require 2 separate islet infusions from 2 separate donors. Immediately before the first transplant, patients will be given anti-rejection (immune suppressing) drugs, including tacrolimus and sirolimus (orally) and daclizumab (intravenously). The islets will be infused into the liver through a tube placed in the portal vein. Heparin (a medication to prevent blood clots) will be administered with the islet infusion. A longer-acting form of heparin will also be given by daily injections during the next week after each transplant. After surgery, patients will receive insulin intravenously for 24 hours. Patients will have an abdominal ultrasound and blood tests to determine liver function. If fewer than 10,000 islets were transplanted, patients will continue insulin treatment, with the dosages adjusted if necessary to account for the transplanted islets. They will take daclizumab every 2 weeks for 8 weeks and tacrolimus and sirolimus daily. Patients will be given antibiotics to prevent infections. Blood tests to determine how much immunosuppressant drug is in the blood will be performed until the drug is at a stable level. Periodically there will be tests to see if the islet cells are functioning. Blood will be drawn to check drug levels and for other tests routinely. Daily insulin requirements will be checked, and these will be recorded monthly. Patients will be followed for at least 1 year post last islet transplantation. Additional follow-up may be provided at least annually for up to 9 years post first transplantation.